The new "buzz" or theory in psychology is that children's peers are more important in shaping their personality than parents are. But a 13-year study of adrenal stress, says home life is much more important for mental and physical health.

Mark Flinn, from the University of Missouri, has been studying the relationship between stress and health in children. He maintains that two of the best ways to measure stress are by asking questions and by measuring the adrenal hormone cortisol in saliva.

• Since 1988, Flinn has collected more than 25,000 saliva samples from 287 children in the same rural village on a Caribbean island for an average of 96 samples per child.

• He has tracked the children's growth, measured their immunoglobulin levels to see if their immune systems are healthy, checked their health records and sent out an assistant to see who's sick.

• Perhaps most importantly, he has watched, listened and asked questions in order to really understand what is happening in their lives.

His results are a compelling rebuttal to the 1998 theory proposed by Judith Harris in The Nurture Assumption, which states that parents have very little power to shape a child's character and basically "lets parents off the hook" for their children's problem behavior. If the theory is correct, parents can all relax, put their kids in day care, and stop worrying that a little scolding will damage them for life. In summary:

• From his more than 25,000 data points, he has come to the conclusion that family matters more than anything else in a child's life.

• When a family has problems, it sends stress hormones coursing through a child's system.

• When family members get along, or have numerous relatives to call on, they can shelter a child from the worst social upheavals in the outside world. Emotionally and physiologically, family life is paramount in a child's health.

The island where the study is being conducted is an ideal place to study these stresses, since many incidental sources of stress are naturally filtered out. There is no traffic, no rat race, and no threat of war.

"In the village, illness among children increases more than twofold following significant stress", says Flinn.

The reason for this is a complex biological process. When a person is in trouble, Flinn explains, the brain automatically sends signals to the sympathetic nervous system, initiating a "fight or flight" response. This response may be summed-up as follows:

• First adrenaline and then cortisol are secreted by the adrenal glands, revving up the body and then sustaining the energy flow to different systems.

• The lungs pump faster and the heart starts to race;

• Blood pressure rises, charging up the muscles and sharpening the mind;

• The stomach gets jumpy and the rush of endorphins numbs the body.

• The appetitite, libido, and immune system shut down, and the energy they would normally consume is diverted to muscles that will help the body fight the immediate threat.

This is all well and good-unless the perceived threat persists. In that case, adrenaline washes out of the body quickly, but cortisol may linger for days, weeks, or even years, keeping the immune system and other important functions depressed.

• Children are especially vulnerable to stress, says Robert Sapolsky, a stress researcher at Stanford University.

• In the long term, too much cortisol can slow down a child's growth, brain development and sexual maturity.

• In the short term, it can make a child prone to infections.

As an illustration of something he has seen time and again, Flinn describes a significant conflict within a group of children. Following this, he collected saliva from each of the participants, none of whom had high levels of cortisol. "And this is typical of mild peer conflicts" says Flinn.

Several weeks later, one of the children from that previous conflict returned home late from a shopping trip and was scolded by her mother. This time her saliva told a different story. Despite the fact that she quietly went about her school work afterward, her salivary cortisol level rose 60% above normal.

Flinn maintains that his results consistently show that families cause more stress than peers do. Only major fights with friends elevate cortisol levels as much as family troubles do.

• According to Flinn "There is nothing more important to a child than figuring out what makes those close to them happy, and what makes them sad."

• Flinn has found that children who live with both biological parents clearly do best. They have lower average cortisol levels, weigh more, and grow more steadily than those living with stepparents or single parents with no support from kin.

• Flinn has also found that boys from households without fathers have cortisol levels that are too low in infancy and that they grow slower than boys with fathers at home.

• Chronically high cortisol levels in children are very dangerous because it can actually cause permanent damage.

In Romania, for instance, orphans raised under the dictatorship of Nicolae Ceausescu were so completely neglected that they became withdrawn and tempermental, and were prone to rocking in place and staring blankly at visitors.

Psychologist Elinor Ames, of Simon Fraser University in British Columbia, studied two groups of these Romanian orphans:

• Those in the first group were adopted by American families by the age of 4 months'.

• The second group spent eight months or more in a orphanage.

• Three years after adoption, the children in the first group had caught up to their peers in terms of size and maturity.

• Many of those who spent the longest time in the orphanage still suffered from depression and withdrawal.

The difference between Judith Harris' "Nurture Assumption" theory and the findings of Mark Flinn may partly be a function of the different cultures they study. In the United States, families are an infant's first peer group, but children soon grow out of them. Without cousins, grandparents, and other relatives nearby to fill out their lives, they have to find their role models on the playground. In a more traditional community studied by Flinn, however, families tend to be much larger and close-by and kin-networks are extensive enough to guide and support children well past adolescence.

Discover August, 2000